The solution is:

```
if k == 1 and n <= 9:
return [] if n <= m else [[n]]
result = []
for i in range(m + 1, 10):
suffix = self.combinationSum3(k - 1, n - i, i)
result += [[i] + _ for _ in suffix] if suffix else []
return result
```

I think the code:

```
result = []
for i in range(m + 1, 10):
suffix = self.combinationSum3(k - 1, n - i, i)
result += [[i] + _ for _ in suffix] if suffix else []
return result
```

can be replace by one line code.